The invention relates to a fluorescence probe, in particular to an organic compound based on gallocyanine and application thereof. The structural formula of the organic compound based on the gallocyanine is shown in a first formula, and the compound is used for carrying out linkage detection on a mitochondrial outer membrane. The compound can be taken as the fluorescence probe for detecting MAO-Blevels in and out of cells so as to have an important biomedicine meaning on deeply researching the kinetic mechanisms of the way of MAO-B for catalyzing monoamine substances in a living body, and theproduction and accumulation process of catalysate and especially have an important biomedicine meaning on the physiological action of MAO-B in the living body and the influence of the catalysate to the living body. The formula is shown in the specification.